These crops account for roughly 72 percent of total conventional pesticide use in U.S. agriculture. This report discusses “conventional” pesticides defined by the EPA as substances developed and produced primarily or only for use as pesticides and excludes sulfur, petroleum distillate, sulfuric acid, and hydrated lime. In addition to data described above, the study used pesticide expenditure data covering all U.S. agriculture drawn from ERS publications.

Pesticide expenditures in U.S. agriculture, 1960-2008

Nominal expenditures on all pesticides used in U.S. agriculture (box fig. 2.1), increased steadily through most of the last half-century. In real terms (constant 2008 dollars, adjusted for inflation), pesticide expenditures increased five-fold between 1960 and 2008. However, 2008 expenditures remain well below the 1998 peak (in real terms).

Value of average product of pesticides for selected crops and years

Per-acre pesticide expenditures vary widely, generally increasing with the per acre value of the crop. For example, while corn and soybean farmers spend between $17 and $26 per acre, cotton farmers spend more than $65 per acre, and producers of potatoes (a high-value commodity) spend nearly $200 per acre (box table 2.1). Pesticide expenditures for many fruits and vegeta¬bles are even higher—$842 per acre for tomatoes and $1,588 per acre for strawberries in 1994 (Fernandez et al., 1998).

Pesticide use in U.S. agriculture, 21 selected crops, 1960-2008

Pesticide use more than tripled between 1960 and 1981. Herbicide use increased more than tenfold (from 35 to 478 million pounds) as more U.S. farmers began to treat their fields with these chemi¬cals. By contrast, insecticide use declined from 114 million pounds in 1960 to 97 million pounds in 1981, and fungicide use increased only slightly (from 25 to 27 million pounds).

Corn acres treated with pesticides, 1952-2008

While farmers have used insecticides and fungicides for many years, the widespread use of herbicides is a more recent phenomenon, as weed control was previously achieved by cultivation and other methods. Only 10% of U.S. corn acres planted were treated with herbicides in 1952. By 1976, herbicide use had grown to 90% of corn acres planted. Growth slowed in subsequent years, reaching 95% in 1982 before stabilizing at around 98% in recent years.

Soybean acres treated with pesticides, 1966-2006

Increasing crop acreage also increased pesticide use. Total planted acreage of corn, cotton, potatoes, wheat, and, in particular, soybeans increased from the early 1960s to early 1980s, from 178 to 256 million acres. However, from 1960 to 1970, pesticide use increased faster than crop acreage, reflecting the effects of increasing share of crop acreage treated.

Price indices, 1965-2008: crops, wages, fuels and pesticides

Relative price trends for crops, pesticides, and other inputs have influenced the cost effectiveness of pesticides and the amount used, given the comparative effects of different pesticides, non-pesticide practices and management systems on pests and damages, which can also change over time. Overall, the NASS pesticide price index fell relative to the NASS wage and fuel indices from 1965 to 2008, while it increased relative to the NASS crop price index in some years and decreased in others, with essentially the same ratio between the pesticide and crop price indices in 1965 and 2007.

Agricultural input price indices, 1990-2008

Since 1990, NASS insecticide and fungicide price indices have risen more rapidly than the herbicide price index. Nonetheless, because herbicides, particularly atrazine and glyphosate, dominate the pesticide market, we can identify underlying trends in pesticide prices by tracking major herbicide prices. Among major agricultural herbicides, prices have risen sharply only for metolachlor; the price of atrazine grew only 1% per year and the price of glyphosate actually fell. In fact, in real terms, herbicide prices have fallen since 1990.

Pesticide use by active ingredient, 1968

There have been shifts in the herbicide active ingredients applied to major crops, as well as reductions in insecticide use. In 1968, atrazine and 2,4-D were among the top five pesticides used, but the other three were insecticides: toxaphene, DDT, and methyl parathion.

21 selected crops in 1968, percent total pounds of a.i. applied. This graph shows the top pesticide a.i. (herbicide=H, insecticide=I) used in 1968.

Due to the substantial benefits provided to farmers (Carpenter and Gianessi, 1999; Fernandez- Cornejo and Caswell, 2006), herbicide-tolerant seed adoption was most rapid and widespread among U.S. soybean farmers. By 2008, over 90% of soybean acres were planted with herbicide-tolerant seeds.

Insecticide use by active ingredient, 1968

Higher pest pressure in some years resulted in higher rates of insecticide application. As some older insecticides became less effective due to pest resistance, farmers applied at higher rates and/ or used new insecticides. DDT and toxaphene (used primarily in cotton production) dominated insecticide use in 1968.

21 selected crops in 1968, percent total pounds a.i. applied. This graph shows the top pesticide a.i. used in 1968.

Insecticide use by active ingredient, 2008

Chloropyrifos and aldicarb became especially important in recent years.16 Newer insecticides applied at low rates, such as synthetic pyrethroids (e.g. permethin and cypermethrin) and neo-nicotinoids (e.g., imidicloprid and clothianidin), have become widely used. (Osteen and Fernandez-Cornejo (2013) provide a more detailed discussion of changing insecticide use over time.) Some insecticides are now applied as seed treatments and are not generally captured by pesticide use surveys.

21 selected crops in 2008, percent total pounds a.i. applied. This graph shows the top pesticide a.i. used in 2008.

Insecticide use for corn production, which had peaked in the late 1970s and 1980s at 0.35-0.45 pound per acre, declined throughout the 1990s and 2000s to under 0.05 pound per planted acre in recent years.

Total pesticide use, as well as the specific active ingredients used (for example, with novel target sites of action or improved toxicological profiles), has changed considerably over the past five decades.

Pesticide use on the 21 crops analyzed in this report rose rapidly from 196 million pounds of active ingredient (a.i.) in 1960 to 632 million pounds in 1981, largely because of the increased share of planted acres treated with herbicides to control weeds. In addition, the total planted acreage of corn, wheat and, in particular, soybeans increased from the early 1960s to early 1980s, which further increased herbicide use. Most acres planted with major crops (particularly corn and soybeans) were already being treated with herbicides by 1980, so total pesticide use has since trended slightly downward driven by other factors, to 516 million pounds in 2008 (the most recent year for which we have enough complete data).

The pesticide types applied by U.S. farmers for the 21 crops analyzed changed considerably from 1960 to 2008. Insecticides accounted for 58% of pounds applied in 1960, but only 6% in 2008. On the other hand, herbicides accounted for 18% of the pounds applied in 1960 but 76% by 2008.